WO2018192122A1 - Method for mixed acid leaching and recovery of positive electrode materials of waste lithium ion batteries - Google Patents

Abstract

A method for mixed acid leaching and recovery of metal components in positive electrode materials of waste lithium ion batteries. The method comprises: performing coarse crushing and drying treatment on waste materials; performing pre-leaching on the waste materials by using a mixed acid containing a reduction agent to obtain pre-separated residues; ball milling the pre-separated residues, performing primary leaching and secondary leaching, mixing the primary and secondary leachates and the pre-leachate, adjusting the pH value of the mixture, and performing suction filtration to obtain aluminum hydroxide and raffinate containing cobalt and lithium; adjusting the pH value of the raffinate containing cobalt and lithium at a high temperature, and performing suction filtration to obtain cobalt hydroxide and raffinate containing lithium; concentrating the raffinate containing lithium at a high temperature, and adding a saturated sodium carbonate solution to obtain high-purity lithium carbonate; and recovering aluminum foil. The process utilizes a mixed acid leaching agent, has high leaching efficiency, can acquire high-purity aluminum, aluminum hydroxide, cobalt hydroxide, and high-purity lithium carbonate (the purity being up to 99.9%) step by step, achieves efficient recovery, overall recovery and collaborative recovery of high-value metals in waste lithium-ion batteries, and has a good application prospect.

Description

Mixed acid leaching and recovery method for waste lithium ion battery cathode material Technical field

The invention belongs to the technical field of secondary resource recycling and recycling economy, and particularly relates to a mixed acid leaching and recycling method for a metal component in a cathode material of a waste lithium ion battery.

Background technique

With the innovation of energy storage and supply methods, the application range of lithium-ion batteries has become more extensive, and its applications involve electronic products, automobiles, aerospace and many other fields. The promotion and use of new lithium-ion batteries overcomes the negative environmental impacts of traditional energy supply and storage methods and reduces energy storage costs. However, according to the statistics of the International Federation of Technology, the average service life of lithium-ion batteries for mobile power equipment is only 2 to 3 years, and the average life of lithium-ion batteries for electric vehicles is only 5 to 8 years. Therefore, the widespread use of lithium-ion batteries is bound to produce a large number of waste battery products, which contain a variety of heavy metal elements and organic electrolytes, which can cause serious water, air and soil pollution if not handled properly. On the other hand, waste batteries contain high-value metal elements such as lithium, cobalt, manganese, nickel, and aluminum. Among them, cobalt and nickel are rare precious metals, and lithium is a strategic metal, which has high recovery value. Therefore, proper disposal and recycling of used lithium-ion batteries can not only avoid their environmental hazards, but also obtain better economic benefits.

At present, researchers at home and abroad have carried out a lot of research and discussion on the treatment and recycling of waste lithium-ion batteries. Among them, hydrometallurgical treatment methods have the advantages of high recovery efficiency, simple process, easy process control, etc., and have received extensive attention. . Patent CN102676827A discloses a method for recovering valuable metals from a nickel-cobalt-manganese lithium battery, and a nickel-cobalt-manganese composite carbonate is obtained by solvent sonication and oxidative acid leaching. CN105331819A discloses a method for recovering Co ₃ O ₄ from a waste lithium cobalt oxide battery cathode material, and the separation and recovery of Co element is achieved by organic acid leaching and organic extraction. CN103199230A discloses a process for reversely recovering lithium nickel manganese oxide from waste lithium battery as raw material, first obtaining nickel manganese oxide by using acetate complexing agent and electrolysis method, and then calcining with lithium source to obtain lithium nickel manganese oxide. . CN103400965A discloses a process for preparing lithium nickel cobaltate by reverse recycling a waste lithium ion battery, and preparing lithium nickel cobaltate by a process similar to the patent CN103199230A. CN101599563A discloses a method for efficiently recovering a positive electrode active material in a waste lithium battery, and obtains a metal material such as copper or aluminum in a used battery by an improved acid leaching and alkali solution adjustment method. CN101212074A discloses a method for recovering a positive electrode material of a lithium ion battery, which recovers valuable elements in the positive electrode material by an organic solvent soaking process. CN101217206A discloses a high-efficiency peeling method for collecting current in a waste lithium battery, which is mechanically crushed to 1 to 5 cm of a battery of a waste lithium battery, and heat-treated at 150 to 600 ° C, and the powder after heat treatment is obtained by vibration screening. Copper and aluminum sheets. The aluminum hydroxide is then partially recovered by dissolving the upper portion of the sieve with a 2 to 4% NaOH solution. CN201310123337.7 discloses a method for obtaining a positive electrode and a negative electrode material of a used battery by a method using a combination of an alkali solution, an organic acid and an organic solvent. CN201310123337.7 and CN201510773893.8 use organic acid (organic carboxylic acid) leaching to realize the separation and recovery of cobalt in waste batteries. CN201510242788.1 The organic acid (organic carboxylic acid) leaching method containing a reducing agent realizes low-cost separation of metal elements in the waste battery waste scrap.

The disclosed waste lithium ion battery treatment and recovery method mainly uses alkali leaching, organic acid leaching, alkali-acid mixed immersion, organic acid-organic solution combination immersion, etc. to selectively or completely leaching metal elements in the battery cathode material, and then A metal element, a metal compound, a positive electrode material, or the like is obtained by extraction, precipitation, displacement, distillation, and the like. After strict process parameter control, although the process can recover metal products, the treatment and recovery process is often accompanied by secondary pollution, high requirements for leachate, low product purity, high production cost, complicated process, and difficult industrial scale. Environmental and technical issues. At present, there is no efficient leaching and effective recovery of valuable metals in the cathode materials of waste lithium ion batteries at the industrial level.

Summary of the invention

In view of the deficiencies of the existing waste lithium ion battery recycling technology, including the complicated recycling process, low recovery efficiency, high demand for leachate, secondary pollution, difficulty in comprehensive recovery of valuable metals, etc., the present invention aims to provide a waste lithium A mixed acid leaching and recovery method for a metal component in an anode material of an ion battery, which can easily and efficiently leaching Li and Co ions, and recover high-purity lithium carbonate, cobalt hydroxide, aluminum hydroxide, pure aluminum, and the like. The mixed acid and the reducing agent in the invention have wide source range, low raw material price, high leaching efficiency, strong recycling process, simple process, low equipment requirement, and can gradually obtain high-purity aluminum metal, aluminum hydroxide, cobalt hydroxide, High purity lithium carbonate (purity of 99.9%). The mixed acid is one or a mixture of organic and/or inorganic acids, and thus the leaching agent is not limited to a mineral acid or an organic acid. By adding a reducing agent, the leaching efficiency of the mixed acid leaching agent is greatly improved, and the efficient and comprehensive recovery of valuable metals in the waste lithium ion battery is realized, the treatment cost is reduced, and the application prospect is good.

To this end, the present invention employs the following technical solutions:

A method for mixing and recovering metal components in a cathode material of a waste lithium ion battery, comprising the following steps:

(1) coarsely crushing and drying the lithium cobaltate cathode scrap;

(2) pre-leaching the positive electrode waste with a mixed acid containing a reducing agent, and filtering to obtain an aluminum foil, a pre-separation slag and a pre-dip;

(3) The aluminum foil obtained in the step (2) is cleaned to obtain a clean aluminum foil and recycled;

(4) After the pre-separation slag ball obtained in the step (2) is ball milled, the primary and secondary leaching are continued, the pre-leaching liquid, the primary leaching liquid and the secondary leaching liquid are mixed and adjusted to pH, and the aluminum hydroxide and the cobalt-containing lithium-containing residual liquid are obtained by suction filtration. ;

(5) The cobalt-containing lithium-containing residual liquid obtained in the step (4) is adjusted at a high temperature, and is filtered by suction to obtain cobalt hydroxide and a lithium-containing residual liquid;

(6) The lithium-containing residual liquid obtained in the step (5) is subjected to high-temperature concentration treatment, and a saturated sodium carbonate solution is added to obtain a white precipitate. After suction filtration, washing and drying, a high-purity lithium carbonate solid is obtained.

Step (1) crushing the lithium cobaltate cathode scrap into pieces of 1 to 20 mm × 1 to 20 mm, the drying treatment temperature is 50 to 200 ° C, and the drying treatment time is 2 to 24 hours;

Preferably, the lithium cobaltate cathode scrap is broken into pieces of 5-15 mm×5-15 mm;

Preferably, the drying treatment temperature is 75 to 175 ° C;

Preferably, the drying treatment time is 2 to 15 hours.

Step (2) pre-leaching the positive electrode waste with a mixed acid containing a reducing agent, the acid concentration is 0.1 to 15 mol/L, the mass percentage of the reducing agent is 0.1 to 20%, and the leaching S/L is 1 to 500 g. /L, the leaching temperature is 5 to 100 ° C, the leaching time is 5 to 480 min, and the stirring speed is 0 to 2000 rpm;

Preferably, the acid concentration is 2 to 4 mol / L;

Preferably, the mixed acid is one or a mixture of sulfuric acid, hydrochloric acid, nitric acid, trichloroacetic acid, trifluoroacetic acid, citric acid, formic acid, acetic acid organic and/or inorganic acid;

Preferably, the reducing agent has a mass percentage of 2 to 8%;

Preferably, the reducing agent is one or a combination of sodium sulfite, sulfurous acid, sodium thiosulfate or hydrogen peroxide;

Preferably, the leaching S/L is 80-150 g/L;

Preferably, the leaching temperature is 30 to 80 ° C;

Preferably, the stirring speed is 100 to 500 rpm.

In the step (4), the mesh of the ball mill is 20 to 1000 mesh.

The ball-milling slag obtained in the step (4) is subjected to primary and secondary leaching, and the acid concentration is 0.1 to 15 mol/L. The reducing agent has a mass percentage of 0.1 to 20%, a leaching S/L of 1 to 500 g/L, a leaching temperature of 5 to 100 ° C, a leaching time of 5 to 480 min, and a stirring speed of 0 to 2000 rpm; Mixed with one or more of organic and/or inorganic acids;

Preferably, the acid concentration is 2 to 4 mol / L;

Preferably, the mixed acid is preferably one or more of sulfuric acid, hydrochloric acid, nitric acid, trichloroacetic acid, trifluoroacetic acid, citric acid, formic acid, acetic acid;

Preferably, the reducing agent has a mass percentage of 2 to 8%;

Preferably, the reducing agent is one or a combination of sodium sulfite, sulfurous acid, sodium thiosulfate or hydrogen peroxide;

Preferably, the leaching S/L is 80-150 g/L;

Preferably, the leaching temperature is 30 to 80 ° C;

Preferably, the stirring speed is 100 to 500 rpm.

Step (4) mixing the pre-leaching liquid, the primary leachate, the secondary leachate and adjusting the pH to 3 to 9, and extracting the aluminum hydroxide and the lithium-containing lithium-containing residual liquid by suction filtration;

Preferably, the pH is adjusted to 5-6.

Step (5) The alkali solution containing the cobalt-containing lithium residue at a high temperature is adjusted to be one or a mixture of sodium hydroxide and ammonia water; the stirring speed is 0 to 2000 rpm; the stirring adjustment time is 0.5 to 72 hours; Adjusting the pH of the temperature is 15 ~ 100 ° C;

Preferably, the alkali solution has a concentration of 0.1 to 10 mol/L;

Preferably, the stirring speed is 100 to 500 rpm;

Preferably, the stirring adjustment time is 2 to 12 hours.

Step (6) The purity of the lithium carbonate separated by the addition of the saturated sodium carbonate solution to precipitate the lithium carbonate is higher than 99.9%; the precipitation temperature is preferably 15 to 100 ° C; the precipitation stirring speed is preferably 0 to 2000 rpm; and the precipitation stirring adjustment time is preferably It is 0.5 to 72 hours; the temperature of the water used for washing is 30 to 100 °C.

The precipitation stirring speed is further preferably 100 to 500 rpm;

The molar ratio of carbonate ions to lithium ions in the solution added to the saturated sodium carbonate solution is preferably from 1 to 3:2.

As a preferred technical solution, the mixed acid leaching and recovery method of the metal component in the positive electrode material comprises the following steps:

(1) The lithium battery positive waste is broken into pieces of 5 to 15 mm × 5 to 15 mm, and the drying temperature is 75 ~ 175 ° C, drying treatment time is 2 ~ 15h;

(2) The positive electrode waste is preliminarily leached with a mixed acid containing a reducing agent, and filtered to obtain an aluminum foil, a pre-separation slag, and a pre-leaching liquid. The mixed acid is one or a mixture of organic and/or inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, trichloroacetic acid, trifluoroacetic acid, citric acid, formic acid, acetic acid, etc., and the acid concentration of the leaching solution is 2 to 4 mol/L. The reducing agent has a mass percentage of 2 to 8%, a leaching S/L of 80 to 150 g/L, a leaching temperature of 50 to 80 ° C, a leaching time of 5 to 480 min, a stirring speed of 100 to 500 rpm, and a reducing agent of sodium sulfite. a combination of one or more of sulfurous acid, sodium thiosulfate or hydrogen peroxide;

(3) The aluminum foil obtained in the step (2) is cleaned to obtain a clean aluminum foil and recycled;

(4) The pre-separation slag ball mill obtained in the step (2) (the number of mesh-milled sieves is 20 to 1000 mesh) is subjected to primary and secondary leaching, and the pre-leaching liquid, the primary leaching liquid, and the secondary leaching liquid are mixed and adjusted to pH. The aluminum hydroxide and the lithium-containing lithium-containing residual liquid are obtained by suction filtration; the pre-separation slag ball milling time is 2 to 5 hours. The acid concentration of the leachate is 2 to 4 mol/L, the mass percentage of the reducing agent is 2 to 8%, the leaching S/L is 80 to 150 g/L, the leaching temperature is 50 to 80 ° C, and the leaching time is 5 to 480 min. The speed is 100-500 rpm, and the reducing agent is one or a combination of sodium sulfite, sulfurous acid, sodium thiosulfate or hydrogen peroxide. The mixed acid is sulfuric acid, hydrochloric acid, nitric acid, trichloroacetic acid, trifluoroacetic acid, lemon. One or several kinds of organic and/or inorganic acids such as acid, formic acid, acetic acid;

(5) The cobalt-containing lithium-containing residual liquid obtained in the step (4) is adjusted in pH at a high temperature, and suction-filtered to obtain cobalt hydroxide and a lithium-containing residual liquid. The solution for adjusting the pH at a high temperature is one or a mixture of sodium hydroxide and ammonia water, the alkali concentration is 0.1 to 10 mol/L, the stirring speed is 100 to 500 rpm, the stirring adjustment time is 2 to 12 hours, and the pH is adjusted. 10 to 90 ° C;

(6) The lithium-containing residual liquid obtained in the step (5) is subjected to high-temperature concentration treatment, and a saturated sodium carbonate solution is added to obtain a white precipitate. After suction filtration, washing and drying, a high-purity lithium carbonate solid is obtained. The precipitation temperature is 15 to 100 ° C, the stirring speed is 100 to 500 rpm, the stirring adjustment time is 2 to 12 hours, the molar ratio of the added carbonate ions to the lithium ions in the solution is 1 to 3:2, and the temperature of the washing water is 90. ~100 °C.

Compared with the prior art, the beneficial effects of the present invention are:

(1) The mixed acid and the reducing agent of the present invention have a wide range of sources, low raw material prices, and high leaching efficiency. The mixing of the mixed acid and the reducing agent can effectively leach the high-value metal components Li and Co in the positive electrode material. The complicated process of separating and purifying the metal components of the prior art is simplified, and the production cost is reduced;

(2) The mixed acid of the present invention is sulfuric acid, hydrochloric acid, nitric acid, trichloroacetic acid, trifluoroacetic acid, citric acid, One or several kinds of organic and/or inorganic acids such as formic acid and acetic acid. The mixed acid leaching agent can be prepared by a mixed method of organic and/or inorganic acid, and the additive content is low, and the raw material threshold is lower than that of the simple organic acid leaching agent;

(3) The method for comprehensively recovering metal components in the positive electrode material provided by the invention has strong operability, simple process flow and low equipment requirement, and can obtain high-purity aluminum metal, aluminum hydroxide, cobalt hydroxide and high-purity lithium carbonate step by step. The purity is 99.9%).

DRAWINGS

1 is a process flow diagram of mixed acid leaching and recovery of metal components in a cathode material of a waste lithium ion battery according to the present invention.

detailed description

The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood by those skilled in the art that the described embodiments are only to be construed as illustrative and not restrictive.

A method for mixing and recovering metal components in a cathode material of a waste lithium ion battery, as shown in FIG. 1, the preferred process comprises the following steps:

(1) The lithium battery positive waste is broken into pieces of 5 to 15 mm × 5 to 15 mm, the drying treatment temperature is 75 to 175 ° C, and the drying treatment time is 2 to 15 hours;

(2) The positive electrode waste is preliminarily leached with a mixed acid containing a reducing agent, and filtered to obtain an aluminum foil, a pre-separation slag, and a pre-leaching liquid. The mixed acid is one or a mixture of organic and/or inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, trichloroacetic acid, trifluoroacetic acid, citric acid, formic acid, acetic acid, etc., and the acid concentration of the leaching solution is 2 to 4 mol/L. The reducing agent has a mass percentage of 2 to 8%, a leaching S/L of 80 to 150 g/L, a leaching temperature of 50 to 80 ° C, a leaching time of 5 to 480 min, a stirring speed of 100 to 500 rpm, and a reducing agent of sodium sulfite. a combination of one or more of sulfurous acid, sodium thiosulfate or hydrogen peroxide;

(3) The aluminum foil obtained in the step (2) is cleaned to obtain a clean aluminum foil and recycled;

(4) After the pre-separation slag obtained by the step (2) is ball-milled (the number of meshes of the ball milled sieve is 20 to 1000 mesh), and the primary and secondary leaching are performed, and the pre-leaching liquid, the primary leaching liquid, and the secondary leaching liquid are mixed and adjusted to pH. The aluminum hydroxide and the cobalt-containing lithium residue were obtained by suction filtration. The pre-separation slag ball milling time is 2 to 5 hours. The leaching mixed acid is one or a mixture of organic and/or inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, trichloroacetic acid, trifluoroacetic acid, citric acid, formic acid, acetic acid, etc., and the acid concentration of the leaching solution is 2 to 4 mol/L. The mass percentage of the agent is 2 to 8%, dip The S/L is 80-150 g/L, the leaching temperature is 50-80 ° C, the leaching time is 5-480 min, the stirring speed is 100-500 rpm, and the reducing agent is sodium sulfite, sulfurous acid, sodium thiosulfate or hydrogen peroxide. One or several combinations;

(5) The cobalt-containing lithium-containing residual liquid obtained in the step (4) is adjusted in pH at a high temperature, and suction-filtered to obtain cobalt hydroxide and a lithium-containing residual liquid. The solution for adjusting the pH at a high temperature is one or a mixture of sodium hydroxide and ammonia water, the alkali concentration is 0.1 to 10 mol/L, the stirring speed is 100 to 500 rpm, the stirring adjustment time is 2 to 12 hours, and the pH is adjusted. 10 to 90 ° C;

(6) The lithium-containing residual liquid obtained in the step (5) is subjected to high-temperature concentration treatment, and a saturated sodium carbonate solution is added to obtain a white precipitate. After suction filtration, washing and drying, a high-purity lithium carbonate solid is obtained. The precipitation temperature is 15 to 100 ° C, the stirring speed is 100 to 500 rpm, the stirring adjustment time is 2 to 12 hours, the molar ratio of the added carbonate ions to the lithium ions in the solution is 1 to 3:2, and the temperature of the washing water is 90. ~100 °C.

Example

All of the other embodiments of the present invention, which are based on the embodiments of the present invention, are based on the embodiments of the present invention, and all other embodiments obtained by those skilled in the art without departing from the spirit of the invention are within the scope of the present invention.

Example 1

The 200 g lithium battery positive waste was broken into pieces of 10 mm×10 mm, the drying treatment temperature was 95 ° C, and the drying treatment time was 3 h;

Table 1 Composition of the metal elements of the cathode material of the used lithium ion battery

metal Co Ni Fe Mn Al Li Content (wt.%) 15.33 11.27 8.9 7.4 3.05 2.96

The positive electrode waste is pre-leached with a mixed acid of nitric acid, sulfuric acid (5 vol.%) and citric acid (35 vol.%) containing hydrogen peroxide and sodium sulfite as a reducing agent, and filtered to obtain an aluminum foil, a pre-separation slag and a pre-leaching liquid; The concentration is 3mol/L, the mass percentage of the reducing agent is 5%, the leaching S/L is 100g/L, the leaching temperature is 60°C, the leaching time is 120min, the stirring speed is 150rpm; the aluminum foil, the pre-separation slag and the pre-preparation are obtained. Leachate. The obtained aluminum foil is cleaned to obtain a clean aluminum foil;

After the obtained pre-separation slag was ball milled (the mesh number of the ball milled sieve was 200 mesh), it was mixed with nitric acid, sulfuric acid (5 vol.%) and citric acid (35 vol.%) containing hydrogen peroxide and sodium sulfite as a reducing agent. After primary and secondary leaching, the pre-leaching solution, the primary leaching solution, and the secondary leaching solution are mixed and adjusted to pH; and aluminum hydroxide (purity: 99.7%) and a cobalt-containing lithium-containing residual liquid are obtained by suction filtration. The pre-separation slag ball milling time is 4h; the acid concentration is 3mol / L, the mass percentage of the reducing agent is 5%, the leaching S / L is 100g / L, the leaching temperature is 60 ° C, the leaching time is 200min, the stirring speed is 150 rpm;

The obtained cobalt-containing lithium-containing residual liquid was adjusted to pH 5 with sodium hydroxide at 70 ° C, and suction-filtered to obtain cobalt hydroxide (purity: 99.7%) and a lithium-containing residual liquid. The alkali concentration is 1.5 mol / L, the stirring speed is 150 rpm, and the stirring adjustment time is 4 h;

The obtained lithium-containing residual liquid is concentrated at 90 ° C, and a saturated sodium carbonate solution is added to obtain a white precipitate. After suction filtration, washing and drying, a high-purity lithium carbonate solid (purity 99.94%) is obtained; the precipitation stirring speed is 150 rpm; stirring The conditioning time was 4 h; the molar ratio of carbonate ion addition to lithium ion in the solution was controlled to be 2:1; the water used for washing was 100 °C.

Example 2

The 200 g lithium battery positive waste was broken into pieces of 15 mm×15 mm, the drying treatment temperature was 105 ° C, and the drying treatment time was 4 h;

Table 2 Composition of metal elements of cathode material of waste lithium ion battery

metal Co Ni Fe Mn Al Li Content (wt.%) 10.31 8.71 7.45 7.01 4.35 3.46

The positive electrode waste is pre-leached with a mixed acid of trichloroacetic acid and sulfuric acid (25 vol.%) containing hydrogen peroxide and sodium sulfite as a reducing agent, and filtered to obtain an aluminum foil, a pre-separation slag and a pre-dip; the acid concentration is 2.5 mol/L. The reducing agent has a mass percentage of 3%, a leaching S/L of 80 g/L, a leaching temperature of 55 ° C, a leaching time of 80 min, and a stirring speed of 200 rpm; and an aluminum foil, a pre-separation slag and a pre-leaching liquid are obtained. The obtained aluminum foil is cleaned to obtain a clean aluminum foil;

After the obtained pre-separation slag is ball milled (the mesh number of the ball milled sieve is 200 mesh), the primary and secondary leaching are carried out by using a mixed acid of trichloroacetic acid and sulfuric acid (25 vol.%) containing hydrogen peroxide and sodium sulfite as a reducing agent, and the pre-precipitation is carried out. The leachate, the primary leachate, and the secondary leachate were mixed and adjusted to pH, and suction-filtered to obtain aluminum hydroxide (purity of 99.6%) and a cobalt-containing lithium residue. The pre-separation slag ball milling time is 3h; the acid concentration is 2.5mol/L, the reducing agent mass percentage is 3%, the leaching S/L is 80g/L, the leaching temperature is 55°C, the leaching time is 80min, stirring The speed is 200 rpm;

The obtained cobalt-containing lithium-containing residual liquid was adjusted to pH 6 with sodium hydroxide at 50 ° C, and suction-filtered to obtain cobalt hydroxide (purity: 99.8%) and a lithium-containing residual liquid. The alkali concentration is 1 mol / L, the stirring speed is 200 rpm, and the stirring adjustment time is 2 h;

The obtained lithium-containing residual liquid is concentrated at 70 ° C, and a saturated sodium carbonate solution is added to obtain a white precipitate. After suction filtration, washing and drying, a high-purity lithium carbonate solid (purity 99.92%) is obtained; the precipitation stirring speed is 200 rpm; stirring The conditioning time was 2 h; the molar ratio of carbonate ion addition to lithium ion in the solution was controlled to be 1.5:1; and the water used for washing was 90 °C.

The Applicant declares that the present invention illustrates the process of the present invention by the above-described embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. It will be apparent to those skilled in the art that any modifications of the present invention, equivalent substitutions of the materials selected for the present invention, and the addition of the auxiliary ingredients, the selection of the specific means, etc., are all within the scope of the present invention.

Claims (10)

A method for recovering positive electrode waste of lithium ion battery based on mixed acid leaching, characterized in that the method comprises the following steps: (1) coarsely crushing and drying the lithium cobaltate cathode scrap; (2) pre-leaching the positive electrode waste with a mixed acid containing a reducing agent, and filtering to obtain an aluminum foil, a pre-separation slag and a pre-dip; (3) The aluminum foil obtained in the step (2) is cleaned to obtain a clean aluminum foil and recycled; (4) After the pre-separation slag ball obtained in the step (2) is ball milled, the primary and secondary leaching are continued, the pre-leaching liquid, the primary leaching liquid and the secondary leaching liquid are mixed and adjusted to pH, and the aluminum hydroxide and the cobalt-containing lithium-containing residual liquid are obtained by suction filtration. ; (5) The cobalt-containing lithium-containing residual liquid obtained in the step (4) is adjusted at a high temperature, and is filtered by suction to obtain cobalt hydroxide and a lithium-containing residual liquid; (6) The lithium-containing residual liquid obtained in the step (5) is subjected to high-temperature concentration treatment, and a saturated sodium carbonate solution is added to obtain a white precipitate. After suction filtration, washing and drying, a high-purity lithium carbonate solid is obtained. The method according to claim 1, characterized in that in step (1), the lithium cobaltate positive electrode waste is broken into pieces of 1 to 20 mm × 1 to 20 mm, the drying treatment temperature is 50 to 200 ° C, and the drying treatment time is 2 to 24 hours. Preferably, the lithium cobaltate cathode scrap is broken into pieces of 5-15 mm×5-15 mm; Preferably, the drying treatment temperature is 75 to 175 ° C; Preferably, the drying treatment time is 2 to 15 hours. The method according to claim 1, wherein the step (2) pre-leaching the positive electrode waste with a mixed acid containing a reducing agent, the acid concentration being 0.1 to 15 mol/L, and the mass percentage of the reducing agent being 0.1. ～20%, leaching S/L is 1～500g/L, leaching temperature is 5～100°C, leaching time is 5～480min, stirring speed is 0～2000rpm; Preferably, the acid concentration is 2 to 4 mol / L; Preferably, the mixed acid is one or a mixture of sulfuric acid, hydrochloric acid, nitric acid, trichloroacetic acid, trifluoroacetic acid, citric acid, formic acid, acetic acid organic and/or inorganic acid; Preferably, the reducing agent has a mass percentage of 2 to 8%; Preferably, the reducing agent is one or a combination of sodium sulfite, sulfurous acid, sodium thiosulfate or hydrogen peroxide; Preferably, the leaching S/L is 80-150 g/L; Preferably, the leaching temperature is 30 to 80 ° C; Preferably, the stirring speed is 100 to 500 rpm. The method of claim 1 wherein the number of meshes in the step (4) is from 20 to 1000 mesh. The method according to claim 1, wherein the ball-milling slag obtained in the step (4) is subjected to primary and secondary leaching, the acid concentration is 0.1 to 15 mol/L, and the mass percentage of the reducing agent is 0.1 to 20%. , the leaching S / L is 1 ~ 500g / L, the leaching temperature is 5 ~ 100 ° C, the leaching time is 5 ~ 480min, the stirring speed is 0 ~ 2000rpm; the mixed acid is one of organic and / or inorganic acid or Several kinds of mixing; Preferably, the acid concentration is 2 to 4 mol / L; Preferably, the mixed acid is preferably one or more of sulfuric acid, hydrochloric acid, nitric acid, trichloroacetic acid, trifluoroacetic acid, citric acid, formic acid, acetic acid; Preferably, the reducing agent has a mass percentage of 2 to 8%; Preferably, the reducing agent is one or a combination of sodium sulfite, sulfurous acid, sodium thiosulfate or hydrogen peroxide; Preferably, the leaching S/L is 80-150 g/L; Preferably, the leaching temperature is 30 to 80 ° C; Preferably, the stirring speed is 100 to 500 rpm. The method according to claim 1, wherein the step (4) mixes the pre-leaching liquid, the primary leaching liquid, the secondary leaching liquid, and adjusts the pH to 3 to 9, and suction-filtering to obtain aluminum hydroxide and a cobalt-containing lithium-containing residual liquid; Preferably, the pH is adjusted to 5-6. The method according to claim 1, wherein in step (5), the alkali solution containing the cobalt-containing lithium residue at a high temperature is adjusted to be one or a mixture of sodium hydroxide and ammonia water; the stirring speed is 0～2000rpm; stirring adjustment time is 0.5-72h; adjusting pH temperature is 15-100°C; Preferably, the alkali solution has a concentration of 0.1 to 10 mol/L; Preferably, the stirring speed is 100 to 500 rpm; Preferably, the stirring adjustment time is 2 to 12 hours. The method according to claim 1, characterized in that the purity of the lithium carbonate separated in the step of precipitating the lithium carbonate by adding the saturated sodium carbonate solution in step (6) is higher than 99.9%; the precipitation temperature is preferably from 15 to 100 ° C; The speed is preferably 0 to 2000 rpm; the precipitation agitation adjusting time is preferably 0.5 to 72 h; and the washing water is 30 to 100 ° C. The method according to claim 8, wherein the precipitation agitation speed is further preferably from 100 to 500 rpm. The method according to claim 8, wherein the molar ratio of carbonate ions in the saturated sodium carbonate solution to lithium ions in the solution is preferably from 1 to 3:2.

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